What part of your code is not working?Did you tried to check what is happening on the interface between your PIC and Codec? Probably a measurement first with an Ossciloscope would be good to verify if the voltage is there and changes as expected. Maybe some PIN configuration issue in the PIC. Then you could do a measurement with a Saleae (logic analyser) to see if the signals are changeing as expected.Can you verify that the microphone that use, is needing a bias or not? Not sure how this Codec is working, but maybe this can be turned off or on, or sometimes turned off due to some constraint. So a simple measurement on the analog part of this could also help.